This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Vermiculite was originally discovered six miles northeast of Libby, Montana in 1881. Vermiculite was mined from the early 1920s until W.R. Grace closed the facility in 1990. Unfortunately, vermiculite from the Libby mine was contaminated with a series of naturally-occurring fibrous and asbestiform amphiboles occurring in veins throughout the deposit. Because of the extensive mining and processing of vermiculite and its use in Libby many of the homes and areas surrounding the historical vermiculite processing and mining facilities within Libby are today contaminated with asbestos. In addition, tens of thousands of vermiculite shipments were transported by railroad throughout the northwest United States from Libby during the 70 years of mine operation, in route to supplying nearly 70% of the world[unreadable]s supply of vermiculite. Initial studies were done to determine if tree bark could serve as a reservoir for asbestos fibers. Bark samples collected within the EPA restricted mine area, within the town of Libby, and along the railroad lines west of town revealed significant levels of asbestos fiber content. The consequences of these findings are significant, as the inhabitants of Libby are dependent on locally harvested firewood for residential home heating throughout the winter months. This COBRE proposal is composed of three Specific Aims that will evaluate the role of trees in the Libby valley as reservoirs for asbestos fibers and potential tool to approximate historical exposures. This project will also determine the extent of asbestos contamination (within trees) in Libby and major transportation corridors and the potential of asbestos fiber exposures during firewood harvesting activities.